1. Field of the Invention
The present invention relates, generally, to a quantum dot phosphor for light emitting diodes and a method of preparing the same, and more particularly, to a quantum dot phosphor for light emitting diodes, which includes quantum dots, and a solid substrate on which the quantum dots are supported.
2. Description of the Related Art
In general, quantum dots are a nanosized semiconductor material exhibiting quantum confinement effects. When the quantum dots absorb light from an excitation source and reach an excited energy state, the quantum dots emit energy corresponding to the energy band gap thereof. As such, since the energy band gap of the quantum dots may be controlled by adjusting the size or composition of the quantum dots, energy having various wavelengths may be used.
To synthesize nanocrystals, methods of preparing quantum dots have been attempted using vapor deposition processes, such as MOCVD (Metal Organic Chemical Vapor Deposition) or MBE (Molecular Beam Epitaxy). In addition, a chemical wet process including adding a precursor to an organic solvent to grow crystals has been rapidly developed. In the chemical wet process, when the crystals are grown, the organic solvent is naturally situated on the surface of the quantum dot crystals and thus functions as a dispersant to control the growth of the crystals. Therefore, the chemical wet process may be more easily and inexpensively performed, compared to vapor deposition processes such as MOCVD or MBE, thus uniformly controlling the size and shape of the nanocrystals.
U.S. Pat. No. 6,501,091 discloses a light emitting diode using quantum dots dispersed in a paste matrix as a phosphor. In particular, the above patent describes a method of preparing a polymer having dispersed quantum dots for use in manufacturing a light emitting diode, which includes mixing a monomer, which has high affinity to an organic ligand substituted on the surface of the quantum dots, with the quantum dots in the presence of a small amount of a catalyst, to obtain a mixture, which is then dispensed and then heated. However, in conventional processes of manufacturing a light emitting diode, a monomer having high affinity to the organic ligand of the quantum dots is not used, and also, whether the properties of the polymer are suitable for use in a diode may be unconfirmed. That is, in order to apply the quantum dots to a light emitting diode, the use of a mixture comprising the quantum dots and the paste resin serving as a paste of a conventional phosphor is preferable in view of process stability and reliability. However, in the case where the quantum dots are mixed with the paste resin, the quantum dots are difficult to disperse well in the resin due to low affinity to the resin, and thus, may aggregate as shown in FIG. 1, resulting in reduced light emitting efficiency of the quantum dots.